US2922519A - Automatic inspection and rejection means - Google Patents

Description

"A qua- Jan. 26, 1960 Filed Dec. 5, 1957 S. A. RADLEY AUTOMATIC INSPECTION AND REJECTION MEANS 2 Sheets-Sheet 1 Jan. 26, 1960 s. A. RADLEY 2,922,519

AUTOMATIC INSPECTION AND REJECTION MEANS Filed Dec. 5, 1957 2 Sheets-Sheet 2 INVENTOR United States atent 2,922,519 AUTOMATIC INSPECTION AND REJECTION MEANS Sidney A. Radley, Columbus, Ohio, assignor to Indnstriai Nucleonics Corporation, acorporation of Ohio Application December "5, 1957, Serial-No. 700,881 '3 Claims. or. 209-111 This invention relates to an automatic inspection and defective unit reject-ionsystem 'for an industrial packaging operation; and more particularly it relates to a photoelectric system for checking successive groups of items for a defective item in a group, and for rejecting any group containingone or more defective items.

The invention will be illustrated and described in connection with a filter tip cigarette packaging operation,

although a number of analogous uses and modifications will become apparent to one working in the art of 'automatic or semi-automatic packaging machinery.

In the production of filter cigarettes, the assembly machinery may occasionally :produce one or-more cigarettes complete except'for thefilter plug itself. To forestall adverse customer reaction, the producer finds it necessary to carry out 100 percent inspection of cigarettes, which requires 'a large number of inspectors to provide this one service. The apparatus of the present invention automatically detects and indicates absence of a filter plug in any cigarette going through a packer.

In an exemplary'type of cigarette packer, two channels of cigarettes are gravity fed, each to a conveyor, in parallel'rows '5 cigarettes wide. Each conveyor moves twolayers (ten cigarettes) at a time to the wrapping mechanism. There is a period of about one-half second during which the 'movement of cigarettes toward the conveyors is halted-each time a group of ten is moved toward the wrapping portion of the packer.

The filter ends of't'he' cigarettes are to the outside of the machine. Inaccordance with this invention, a filter detector assembly is mounted infront of each-ofthe two channels of vertically-moving cigarettes, just above the conveyors.

'Thisassemblycontains, in this example, ten photoc'ells arranged so that each looks at a cigarette end while the cigarettes areat'rest, while a light source illuminates the cigarette-ends. A switch, mounted adjacent a reciprocating member'of the packer and actuated thereby, acts-as 'a'trigger device to energize the bank of photocells only when'the cigarettes are'at rest and in al'ign ment with the-respective photocells. In a separate unit is a powersupply and a signal output tube and relay.

Existingpackers ofthe type herein described include a delayand rejection mechanism which preventsapack from-being completedif one or'more-cigarettes are missing from a pack. The same mechanism can be used as part of a filterplug rejection device in connection with thes'ignal output tube and relay of the present invention.

detector and rejection apparatusfor a cigarette packaging machine.

It is also an object to provide electronic and mechanical apparatus in accordance with the above objects which is economical to build, simple to install and maintain, and reasonably fail-safe.

Further objects and advantages of the invention will become apparent in the following detailed description, taken in conjunction with the accompanying drawings in which:

Fig. 1 is a diagrammatic showing of anrexemplar'y type of packaging machine in perspective, specifically 'a cigarette packaging machine, havingautomatic filter plug inspection and packet rejection :means associated therewith in accordance with the present invention.

Fig. 2 is a side elevation, partly in-section, of the photoelectric detector head inconnection'with-a portion of the apparatus of Fig. 1.

Fig. 3 is an electrical schematic diagram of the electronic circuitry'of the defect signaling system.

Referring to Fig. 1, assembledcigarettes, nominally complete with filter plugs, are delivered by manual or automatic conveyor means to a specially designed hopper 19 wherein the cigarettes are assembled in a vertical stack 12. The width of the stack between its respective retaining walls is such that at least cigarettes near the bottom of the'stack lie in strata or horizontal rowsof exactly five cigaretteseach.

A conveyor belt 14 passes under'stack 12, "and 'carries on its periphery a plurality of upstanding cleats as at 16a and 16:). As eachcleat passes under the stack, two successive horizontal rows of cigarettes are slidfrom the bottom-of the stack so that-a group of ten cigarettes as at 18 is carried'forward upon the conveyor to a-wrapping unit 20. I

Thewrapping -machine-20-forms a packet of ten cigarettes as at 22,wrapped in foil or the like, which is carried forward toward a second conveyor 24 which runs at right angles to conveyor "14. 1

The conveyor 24 carries open, partially formed boxes of cardboard or the like as at 26 which are-delivered onto conveyor 24at'suitably spaced intervals by a conventional box-forming or box-unfolding mechanism 28. Since the two conveyors 14 and 24 'a'ndthebox 'formin'g mechanism 28 are driven in mutually timed relation to one another, .aiwrapped packet as at 22is delivered into each box upon its passing the delivery slide 30 which constitutes the'terminus of conveyor 14.

At 32 there is. shown a further slide, identical with slide 30, which constitutes the terminus of another section of the machine (not shown) which is identical with the section thereof indicated by numerals 111-22. The outer boxes as at 26, which are delivered by unit 28, are adapted to contain. two foil-wrapped packets 'as'at 22, one of which-is delivered on slide 30 and the other on slide 32 so as to form an assembly as at 34 comprising a box containing two packets of ten cigarettes each, for a total of'twenty. The assemblies as at 34 continue on conveyor 24 to a closer and sealer machine indicated at 36, which closes and seals the outer'boxes. Completed packages as at 38 issue from the rear'of machine 36 to be assembled for later storage or shipment.

The machinery described is of a known type, powered by conventional intermittent motion drivemeans (not shown). The intermittent drive is necessary due to the need for stopping conveyor 14 while the packets are being wrapped in wrapper 2t), and due to the'need for stopping conveyor 24 while a box as-at 40 is in'alig'nment with a slide as at'32 when a-packet'is tobe delivered thereon.

In accordance with'this invention, a detector head 42 and lamp housing 44 are disposed adjacent thestack 12 of cigarettes at the bottom of hopper 10. It is seen that the bottom of the hopper is cut away to expose the cigarette ends nominally containing filter plugs. This assembly is shown in further detail in Fig. 2, wherein a light source 46 disposed in lamp housing 44 is shown illuminating the filter tip ends of the cigarettes in the third and fourth rows from the bottom of the stack 12. The detector 42 contains ten photocells as at 48 and 50, e.g., cadmium selenide cells, each of which is recessed into a tube as at 52 and 54 to prevent an excess amount of stray light from striking the active end of the photocell. The detector head 42 is vertically spaced from the conveyor 14 a sufiicient distance to allow a cleat 16c carried by the conveyor to clear the same. Normally, each photocell is subjected to a relatively high level of illumination due to the light reflected from a white filter. However, if a filter plug is missing, the photocell sees a relatively dark opening. a

Referring again to Fig. 1, the photocells in detector 42 are all connected by a cable to a console 62 containing suitable electronic circuitry to be described hereinafter. Herein the electrical signals produced by the group of photocells are combined. The console 62 and its contained circuitry are also connected by means of cable 64 to a switch 66 associated with the wrapper mechanism 20. Switch 66 is a means for disabling the operation of the detectors and associated circuitry except when the conveyor 14 and the cigarettes in stack 12 are at rest, thus preventing ambiguous signals from the detectors as a result of stack movement.

When one or more filter plugs in a group of cigarettes presented to the detector are missing, a reject signal is generated by circuitry 62, and this reject signal is transmitted over line 68 to a solenoid 70.

Adjacent to solenoid 70 is a memory drum 72 which is driven by a mechanical connection 74 to the drive system of the machine, so as to rotate in suitable timed relation thereto.

Near its outer rim, the drum 72 carries a plurality of axially slideable plungers as at 76, frictionally engaging bored openings in drum 72; these openings, or ways, being parallel to the axis of drum 72. The plungers extend through the drum and project outwardly from both sides thereof, normally occupying the position shown. Whenthe intermittent motion of the machine stops rotation of thedrum, a plunger is brought into axial alignment with a striker 78 carried by the armature (not shown) of solenoid 70. It is also at this point in the machine cycle where switch 66 energizes the filter plug detector circuits, so that the absence of a filter plug in a cigarette causesthe actuation of solenoid 70. Thereupon the striker78 will push the aligned plunger to a position wherein the right end of the plunger is extended, as is shownby the dotted lines 80. On further rotation of drum 72,. the extended plunger 80 is carried around until it eventually strikes the actuator 82 of a switch 84. Switch 84, may'ofcourse be connected to operate any type of rejection means. In the present instance, however, the switch is connected by means of cable 86 to an interrupt mechanism of conventional design in box former 28 so as to withhold the box as at 87 which would otherwise be delivered to conveyor 24 on schedule to permit the box to contain the packet including the cigarette with the missing filter plug. The pair of unboxed packets may beremoved from conveyor 24 by an operator stationed ahead of the sealer 36, or the packets may proceed onthrough the sealer as in the case of packets 88, to be separated later from the completed packages.

Referring again to the signal delay device, it is seen that as rotation of the memory drum 72 proceeds, the plungersare carried past a wedge member 90 which pushes any extended plungers as at 80 back to the original positlon as of plunger 76.

Fig. .3 depicts the circuitry of the detector head 42, the console 62, switch 66 and the solenoid 'lll'ot Fig. 1.

These circuits are energized from the conventional A.C. power source 100.

A unidirectional voltage for operating the missing filter detector is provided by a power supply comprising a rectifier 104 in series circuit with a pair of resistors 102 and 106. Resistor 102 reduces the peak line voltage to a suitable output voltage level across resistor 106, which output voltage is filtered by a large capacitor 108 connected across resistor 106. When switch 66 is closed, a positive potential with respect to ground line 110 appears on line 112. v I

A plurality of photocells, including 48 and 50 of Fig; 2, and also including a number not shown, up to and including the nth photocell P are connected across lines 110 and 112 in series respectively with load resistors 114; 116 and others to R The photocell anodes 118, 120 and others to A are further respectively connected through diodes 122, 124 and others to D to a common output resistor 126 having its other end grounded on line 110. e r

It is known that when a photocell of the type described is in darkness the current carried by the same is small; that is, the cell exhibits a high impedance. Accordingly, therewill be a high positive potential on the' anode of the cell. On the other hand, when the cell is lighted, its" impedance is reduced, and due to the voltage drop across the load resistor, the anode potential falls to a less posi-' tive value.

The novel circuit of the present invention, comprising the diode coupling of the anodes to the output resistor 126, permits sharp differentiation between the signal output of a plurality (in this example, ten) of photocells all lighted and the output when only one of the group is partially darkened. Bythis means each cell is able to signal its dark condition with a high degree of independence of the lighted condition of the other cells, even though all cells use a common power supply connection and all. have a common output. Because the diodes are asymmetrical conduction devices, the potential. appearing across the output resistor 126 is always substantially equivalent to the potential on the most positively charged anode; that is, the anode of a darkened cell. This higher positive potential may not be distributed to the other anodes, and thereby attenuated, because the diode sub stantially blocks current flow. in that direction.

,Theremainder. of the circuitry in Fig. 3 provides suitable electronic switching means for controlling the energization of the solenoid 70, alsoshown in Fig. 1, in accordance with the signal acrossthe output resistor 126. This rather conventional switch means preferably comprises a thyratron tube 128- having a relay coil 130 in the plate circuit thereof. The cathode-plate .circuit including .the relay coil is connected across the. A.C. power 'source 100. A negative grid bias voltage for thyratro'n 128'is provided by a DC. power supply comprising a rectifier 132, resistor 134, potentiometer 136 and capacitor: 138. The magnitude of the fixed bias voltage is adjustable by means of potentiometer 136. A grid bias-resistor140 and an input resistor 142 in series therewith connect the variable tap of potentiometer 136 to the signal voltage appearing *across the output resistor 126 of the detector circuits. The grid 143 of the thyratron is connected to the junction of resistors 140 and 142, so that the potential on the grid is proportional to the difierence between the fixed bias voltage and the signal .voltage across resistor 126. Potentiometer 136 is set so that when ten perfect cigarettes are presented to the detector, the negative bias on grid-143 is more than suflicient to keep thyratron 128 cut ofi, but when one filter plug is missing the decrease in bias is more than suflicient to allow the thyrat ron to fire, or conduct current. This firing energizes relay which in turn closes its contacts 130a, thus actuating solenoid 70 for the-purpose above described. A rectifier 144 is connected across relay coil 130 to stabilize the operation of the relay.

A neon lamp 146 is connected between lines 110 and 112 to provide an indication of proper operation of the trigger switch 66, so tlrat when the light stops flashing the operator is notified of a malfunction. A failure of any photocell or the light source 46 will result in rejection of every package, also providing an immediate indication of trouble.

It should be understood that many changes and modifications may be made of the embodiment herein described and illustrated, particularly where the invention is to be adapted for use with other types of packaging machinery, either for cigarettes or other similar or very different types of products. Several other and difierent schemes for rejection of defective items may be used. All such changes and modifications are therefore considered to be within the spirit and scope of the invention as is set forth in the appended claims.

What is claimed is:

1. On a production line delivering production items to a packaging station; means for collecting said items into groups each containing a predetermined number of items, an inspection station spaced from said packaging station, means for conveying said groups successively through said inspection station to said packaging station, a light source in connection with said inspection station for illuminating a group of items thereat; a plurality of photoelectric detectors, one such detector corresponding to each item in said group, and each detector responsive to light reflected from said item; a unidirectional voltage source, a plurality of voltage dividers connected across said voltage source, each of said voltage dividers comprising an electrical load impedance and at least one of said photoelectric detectors in series connection therewith; an output impedance having a first terminal connected to one side of said power source, and a second terminal; a plurality of asymmetrical conduction devices, one such device being connected between said second terminal and the junction of said load impedance with said detecting means in one of said voltage dividers; means responsive to the magnitude of the electrical potential across said load impedance for generating a reject signal, means intermediate said inspection station and said packaging station for rejecting a group on receiving 6 said reject signal, and means for transmitting said reject signal to said reject means, said signal transmission means including means for delaying said reject signal pending the arrival on said conveyor of said group at said reject means.

2. The combination as in claim 1 wherein said conveyor means includes intermittent motion means for driving the same and means for disabling a function of said photoelectric detectors when said conveyor is in motion.

3. On a production line delivering production items to a packaging station, means for collecting said items into groups each containing a predetermined number of items, an inspection station spaced from said packaging station, means for conveying said groups successively through said inspection station to said packaging station, a light source in connection with said inspection station for illuminating a group of items thereat; a plurality of photoelectric detectors, one such detector corresponding to each item in said group, and each producing an electrical signal functional of the intensity of light reflected from said item; circuit means for combining said signals from each of said detectors to produce an aggregate signal, means responsive to a characteristic of said aggregate signal for producing a reject signal, means intermediate said inspection station and said packaging station for rejecting a group on receiving said reject signal, means for transmitting said reject signal to said reject means, said signal transmission means including means for delaying said reject signal pending the arrival on said conveyor of said group at said reject means, intermittent motion means for driving said conveyor, and means for disabling a function of said photoelectric detectors when said conveyor is in motion.

References Cited in the file of this patent UNITED STATES PATENTS 1,812,294 Hohn et al June 30, 1931 1,993,619 Nefl? et al. July 23, 1932 2,008,870 Little July 23, 1935 2,209,111 Chalmers July 23, 1940 2,369,794 Phinney et al. Feb. 20, 1945 2,618,386 Samain Nov. 18, 1952 2,696,297 Matthews Dec. 7, 1954 2,726,762 Aubry Dec. 13, 1955

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